1. Field of the Invention
The present invention generally relates to a support ring for the screen of a centrifugal polymer resin pellet dryer. More specifically, the present invention relates to a support ring which interconnects and supports vertical dryer screens of the type which include cylindrical screen sections. The support ring is positioned in spaced relation to an exterior housing of the dryer by brackets, and the screen encloses a driven bladed rotor for removing water from a slurry of water and pellets. The support ring supports adjacent ends of the screen sections from the external housing.
2. Description of the Prior Art
Centrifugal pellet dryers of both the vertical and horizontal type are well known and include an outer housing, a cylindrical screen oriented in the housing and a bladed rotor mounted in the screen for moving a slurry of water and pellets within the screen to enable discharge of water through the screen. A slurry inlet is provided along with an outlet for water and an outlet for the dried pellets. Centrifugal pellet dryers of the vertical type are disclosed in U.S. Pat. Nos. 3,458,045; 4,565,015; 4,896,435 and 5,265,347 commonly owned by the Assignee of this application. In the operation of such dryers, the screen, which is generally in a plurality of sections, usually two, must be maintained in a cylindrical configuration concentric with the periphery of the rotor to obtain efficient and long-lasting operation of the dryer. While the dryers disclosed in the above patents include support rings and other structure for supporting the screen sections, the ring or other structure is not satisfactory to prevent the adjacent ends of the cylindrical screen sections from becoming deformed and no longer in the prescribed cylindrical shape.
In addition to the above mentioned patents, some dryers or material separators are rotated about a horizontal or inclined axis. The following U.S. patents disclose various horizontally disposed or inclined drums having perforated surfaces to separate materials: U.S. Pat. Nos. 264,824; 301,803; 319,572; 533,457; 1,596,428 and 2,536,054. Also, additional vertical screen and conveyor structures are disclosed in U.S. Pat. Nos. 411,799; 4,017,387; 4,178,246; 4,570,359; 4,476,019; 5,187,880 and 5,611,150. These aforementioned patents disclose various screens or perforated members for receiving materials and which rotate or are provided with a rotor interiorly mounted with structures for supporting the stationary screen or perforated member.
Furthermore, manufacturers of commercial pellet dryers have used one and two piece support rings to connect and support screen sections in place within the dryer housing. In particular, the Assignee of this application has commercialized vertical pellet dryers with support rings for interconnecting adjacent ends of screen sections which comprise two semicircular bands forming a circular connecting band. The connecting band is then connected to the dryer housing at various spaced locations. This prior art assembly is described hereinafter in connection with FIG. 7 of the instant drawings.
However, none of the above prior art structures comprise a support ring which has the design or structure to withstand deformation of the connected screen section ends during use of the dryer, and which can be quickly installed or removed, or replaced, when necessary to remove or replace a screen section or gain access to the interior of the dryer.